DEVELOPMENT OF LIQUID CRYSTAL BASED NANOPARTICLE SENSORS

Date

2025-1-9

Author

Karausta, Aslı

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Liquid crystal (LC) exhibits both the flow properties of liquids and long-range orientational ordering of crystalline solids. Since the ordering of LCs can be controlled by the fine scale of energetics, they have remarkable sensitivity. In this study, we used LC to be able to get response to nanomaterials. Firstly, we aimed to examine the interparticle interactions and self-assemblies of nanoparticles by using the confined systems. We used LC droplet as a confined medium and analyzed the interparticle and LC-nanoparticle interactions at LC-aqueous interface by using gold nanoparticles. Then, we developed a method to determine LC configuration within the microwells with shape of circle, square, triangle, rectangle and star. Lastly, we prepared stable, three-dimensional and water insoluble platform for analyzing LC-aqueous interface by using soft-lithography. The LC configuration within microwells was examined under polarized optical microscope, revealing interfacial tilting and defect formation. Sodium dodecyl sulfate (SDS) molecules were used as a model analyte, demonstrating that change in interfacial tilting due to surfactant adsorption. Depending on the interfacial anchoring, metastable configurations having defect structures which were point defects and disclination lines were formed. Also, the response of LC to the adsorption of silica nanoparticles functionalized with silane and dye molecules were studied and found that concentration of dye molecules on the nanoparticle surface, in the range of ppb, could be detected via changes in the tilting at the LC-aqueous interface. These findings suggest a potential for sensor applications, a stable platform was developed for detecting various analytes like molecules or colloids.

Subject Keywords

Liquid Crystal, Confinements, Topological Defects, Sensor, Stability, Sıvı Kristal, Topolojik Kusurlar, Mikro-sınırlandırma, Stabilite, Sensör

URI

https://hdl.handle.net/11511/113413

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Graduate School of Natural and Applied Sciences, Thesis